1. Field of the Invention
The present invention relates to an image processing apparatus provided with a density correction unit.
2. Description of the Related Art
Among conventional image processing apparatuses, there is an apparatus which is provided with a density correction mechanism for the purpose of keeping a stable image density when forming an image onto a medium. Specifically, there is an apparatus which realizes density correction by forming a patch for density measurement (hereinafter, patch) on an intermediate transfer body, detecting a toner accumulation amount of the patch with an optical sensor, and reflecting an obtained density to a value of a density correction table. When such density correction is performed, generally there exists a trade-off in a relationship between correction accuracy and processing speed. That is, when the correction is performed after a necessary and sufficient number of patches are obtained for performing a higher-accuracy density correction, the number of patches is increased and thereby a longer time is required for processing necessary for the correction. Accordingly, sometimes there is generated a downtime during which printing cannot be performed.
Meanwhile, when the correction is performed by using an available number of patches, utilizing a warm-up time for activation or a time between print pages without generating the downtime, the accuracy of the density correction sometimes becomes low because of an insufficient number of patches to be used for the correction.
For this problem, Japanese Patent Laid-Open No. 2010-39477 describes that a density range of the patch to be formed is changed according to environmental temperature change so as to cause a developing characteristic to be corrected efficiently in a vicinity of a target density by the use of an available number of patches without the downtime generation.